Prepend extra `/` for Windows file URLs
Prepend extra `/` for Windows file URLs

douglasduteil/builder,systemjs/builder,richardTowers/builder,jrauschenbusch/builder,Munter/builder,jrauschenbusch/builder,jrauschenbusch/builder,alexandr2110pro/builder,systemjs/builder,richardTowers/builder,ahmedshuhel/builder,alexandr2110pro/builder,tonytanger/builder,matthewbauer/builder,Psvensso/builder,JeroenVinke/builder,systemjs/builder,tonytanger/builder,robwormald/builder,synaptek/builder,douglasduteil/builder,whitneyit/builder,lookfirst/builder,Munter/builder,alexisvincent/builder,alexisvincent/builder,Psvensso/builder,alexisvincent/builder,robwormald/builder,synaptek/builder,buddhike/builder,whitneyit/builder,JeroenVinke/builder,ahmedshuhel/builder,lookfirst/builder,matthewbauer/builder,buddhike/builder